Aspirin

Aspirin is the cornerstone of the treatment of cardiovascular disease. Since there can be complications associated with the use of aspirin, we should use the lowest dose known to be effective. For the prevention of heart attacks and strokes, the lowest effective dose is 75 mg. In the United States, the lowest widely available dose is 81 mg, which seems to be an odd amount.

Before the rise of the modern pharmaceutical industry, chemists used the old English system of measurement. The smallest unit of weight is the grain, which is 65 mg. The standard dose of two aspirin was 10 grains. Each tablet was 5 grains (325 mg). It was thought that the appropriate dose of aspirin for a baby was one-quarter tablet (81 mg). An enterprising manufacturer spared the parents of yore from turning aspirin tablets into heaps of powder attempting to quarter them by formulating “baby aspirin.” To make the product more appealing, the tablets were colored and flavored orange.

There can be serious gastric irritation from aspirin. In an attempt to protect the GI tract, what is now called “low dose adult aspirin” is available with an enteric coating. The unexpected consequence of this coating is that not enough of the aspirin is absorbed. The actual delivered dose of aspirin is not 81 mg; it’s not even the 75 mg generally recognized as the minimum dose needed to prevent cardiovascular events.

Equivalent doses of enteric-coated aspirin are not as effective as plain aspirin, since there appears to be lower bioavailability from the coated product. The pseudoresistance may be more marked in heavier individuals.

I recommend that the patient who needs to take aspirin for the prevention of cardiovascular disease take 81 mg of the immediate release product. There appears to be less gastric irritation if taken with a meal.